From: Jarek Adamski
Date: 2004-07-03
Subject: YABUS.ZX info

I've just finished first tests of YABUS.ZX.

What is YABUS.ZX? Two YABUS slots in small, through
interface, connectable to rear slot of ZX Spectrum.

It could be you wanted to connect some extra interfaces
to ZX Spectrum. You had to join them in "a sequence"
behind Spectrum or disconnecting one before connecting
another, as many of them were non-through. Besides the
connection not alwayst was perfect and you had to do
some experiments with angle of insertion, etc.

Now it can be different, as having YABUS.ZX, you can
connect the extentions easy and easy disconnect them.
(Of course while power off!)

I don't know if you ever try to build your own interface.
Perhaps 8255, perhaps AY, perhaps something more advanced.
My experience says there always were two important
problems:
 - how to connect the signal bus,
 - what to do to keep possibility to connect also
something else (non-through, such as interface of Timex
FDD 3000).

YABUS.ZX removes both these problems at once. Is through
interface and the YABUS slots are easy accessible from
top of its box. The more, the slot I've used allows to
build somethig even on one-side coppered universal board.
I can say more. It is even possible to use universal
board without copper. It is enough it doesn't conduct
and has enough holes!!!

To simplify following description I mention that in YABUS
(as whole) modules called YAMOD are plugged.

To return to my tests. Several years ago I've made
prototipe of YABUS for my Sam Coupe. To have more fun,
I've build a YAMOD with AY-3-8910. I worked and played
music. :-) Now, I've plugged this YAMOD int YABUS.ZX.
It is correctly detected and works!

So I mentioned about a special property of YABUS - the 
hardware independency. The same YAMOD you can plug into
wide range of computers based on Z80 CPU - e.g. ZX
Spectrum, Timex FDD 3000, Sam, MSX, CPC...
Of course not always it makes sense, but is important in
case of some kinds of YAMOD. I didn't try with computers
of other CPU (6502, 68000), but this is also possible.
(I would like to try with Amiga...)

Both the YABUS and most of YAMODs are very simple, so
they are cheap.

I've mentioned that you can easy build an YAMOD. From my
side, I've designed several modules and some more are in
way. They are:
 - YAMOD.ATBUS - IDE multiplexer (drives harddisks, CD
readers, Compact Flash, etc.).
 - YAMOD.EPROG - teoreticly EPROM programmer, but
practically universal parallel interface (30 bits).
 - YAMOD.IDE8255 - simpler (read: slower) IDE multiplexer.
 - YAMOD.ZXINPUT - gives possiblility to connect keyboard
and mouse of PC (seen as Kempston Mouse or Sam Mouse).
Also can generate interrupts on every screen line as Sam
do.
 - YAMOD.KMOUSE - means Kempston Mouse - requires a mouse
from Amiga.
 - YAMOD.FDC765A - floppy driver controller. Will work in
two modes: ZX Spectrum +3 compatibile and ISA (the same
as you connect a ISA Multi I/O card).
 - YAMOD.AYLPT - AY-3-8910 sound interface working in ZX128
and Timex 2068 compatibility. I/O ports are available on
DB25 and 20 pin user slots. Extra option is IIC magistral
and a possibility to add 8kB EEPROM, used by ZXVGS.
 - YAMOD.EPLIP - closely undefined (for me) very fast
parallel interface, with FIFO buffers.
 - YAMOD.8250 - serial interface - as in PC. ZXVGS can use
a PC mouse connected to this module (I know, I have 
prototipe inside my Sam Coupe).
 - YAMOD.8211 - PC-like printer interface.
 - YAMOD.MB02PIO - is a 8255 PIO with DB37 slot, as in MB-02.
 - YAMOD.PCMOUSE - simple RS232 for PC mouse - only 1200bps
and 19200bps.
 - YAMOD.SIO - for radio amateurs - turns your computer into
TNC modem. You need only the BayCom modem at the end. (Not
exactly for ZX Spectrum, but...)
 - YAMOD.ETHERNET - perhaps a bit expensive, but there's a
module (http://www.embeddedethernet.com/), that doesn't need
a PC to work.

Additional informations you can find on:
 http://8bit.yarek.pl/interface/yabus.zx/

I will offer for sale both ready interfaces and DIY kits
boards for them. Full documentation guarranteed in .html
and .jpg files. (Also for Eagle (http://www.cadsoft.de) .sch
and .brd files.) You can also expect support for YAMODs in
ZXVGS and CPM22QED (http://zxvgs.yarek.com/).